1. Field of the Invention
This invention relates to a method for producing bread from preserved dough. In particular, it relates to a method for producing bread of a good quality by baking or drying dough that is especially prepared and then quickly frozen, and thereafter preserved for a long time.
2. Prior Art
Much effort has been made in the past so that freshly baked bread could be eaten at home. Making bread at home is difficult since fermenting dough requires controlling the time, temperature, and humidity to which the dough is subjected, and it needs special skills or knowledge. To enable consumers to eat bread fresh out of an oven, while circumventing the complicated part of the bread-making process, a method has been conceived wherein dough is frozen after a fermentation step and is preserved for an indefinite period, and is then sold to consumers who will then either bake the frozen bread to eat it or who may instead preserve the bread for future consumption. By this method anyone can enjoy fresh bread by merely baking the frozen dough.
The problem with this type of bread has been that dough thus frozen and preserved cannot expand while it is being baked as much as can the ordinary type of bread.
Japanese Patent Early-publication No. 49-41556 discloses a method for freezing dough for bread, doughnuts, or the like. In this patent dough shaped into a desired form is rapidly frozen after a fermentation step. This publication describes avoiding the problem of insufficient dough expansion by applying a chemical intumescent agent (an expansion agent) to the dough.
Japanese Patent Early-publication No. 61-205437 also discloses a method for producing frozen dough in which dough is frozen after a fermentation step. This publication describes avoiding the problem of insufficient dough expansion by applying water, milk, or beaten eggs to the surface of the dough, after the fermentation step, so that the dough can expand sufficiently during the baking step.
The conventional automated bread production method comprises the steps of: (1) mixing the necessary ingredients and kneading them to make a dough mass, (2) measuring and dividing said dough mass into small pieces of a uniform size, (3) shaping said pieces into balls, (4) resting the dough balls for about 25 minutes, (5) degassing the dough balls, (6) shaping the balls into a desired form, (7) fermenting the shaped dough, and (8) baking the shaped dough. Therefore, at least eight steps are required for baking the bread. In this method, the dough is rested or left to stand for about 25 minutes after the dividing step so that the gluten network that was broken during the preceding dividing step can be restored. To improve the restoration of the gluten network in the conventional process, in addition to the resting step, an oxidizing agent such as ascorbic acid and/or potassium bromate is generally mixed with the materials used for the dough. This leads to bread of a good quality. However, freezing such dough for preservation does not give a good quality bread when it is baked after preservation.
Conventionally, the quality of the bread obtained by baking after preservation is considerably lower than bread made from dough which is baked immediately after the fermentation step but without preservation. More particularly, a specific volume of at least from 4 to 4.5 cc/g is generally attained when croissant dough is baked without freezing, while a specific volume of only from 2.5 to 3 cc/g is obtained when the dough is baked after being frozen and preserved. This results in an inferior product that is harder than ordinary bread.
In the prior art croissant dough freezing and preserving processes, the dough greatly expands during a fermentation step, where the dough is typically subjected to a temperature of 34.degree. C., and a humidity of 80%, for 50 minutes, but is greatly deflated during the freezing process, and it does not recover the lost volume in the baking process. Further, when the dough deflates after it expands, the surface of the dough becomes wrinkled and uneven or cracked. This is why inferior bread is produced from dough frozen and preserved according to the prior art processes.
To avoid the deflation causing wrinkles and cracks, in the prior art the dough is subjected to a fermentation time shorter than the time for the conventional bread-making. For instance, if the dough is for a croissant, it is fermented for 30 minutes instead of the conventional time of 50 minutes. In this case, the dough expands less than the dough fermented for the conventional time. Thus, the dough is deflated less in the freezing step than the dough that is frozen after the conventional fermentation period and its surface becomes less wrinkled and smoother. However, the finished bread from such dough does not expand as much as the regular bread baked from the dough of the conventional fermentation step even though it expands a little during the baking step.
An earlier application of the assignee of this invention, U.S. patent application Ser. No. 213,753 now U.S. Pat. No. 4,946,699 discloses a method for producing bread from preserved dough.
After experiments and careful observation of the prior art processes, the inventors of that application had discovered that the damage to the gluten network in dough is the cause for the deflation during the freezing step and the inferior expansion during the baking step. In the method of that application the dough is stretched while being subjected to vibrations so that the dough can be stretched without a pressure being imparted that exceeds the yield point of its elasticity. Thus the gluten network structure is unharmed. Then the dough goes through the step of cutting, shaping, fermentation, and freezing for preserving. After a desired preservation period the dough is baked. Since the dough does not become deflated during the freezing step, and expands further during the baking step, puffy and tasty bread results.